Study On The Growth And Properties Of Stoichiometric Lithium Niobate Doped With Cu

Lithium Niobate owns the advantage of electro-optic,optical property and easy of growth,low cost,stable performance and so on, and is widely applied in the volune holographic storage. However, the composition of LiNbO₃ crystal de- viated from its stoichiometric ratio, the existence of lithium vacancies and antib- it niobium defects, and result in many carrier traps, space charge easily be capt- ured, which led to the disadvantage of crystal response time of long, small coup- ling gain coefficient and anti-light-induced scattering ability of low.Near-stoichiometric crystals simultaneously solve the above disadvantage and still exists the problem of low diffraction efficiency, so that the field of pho- torefractive was restricted.In this paper, using Czochralski method by adding cosolvent in the optimu- m process parameters has been grown the doped near stoichiometric LiNbO₃ crystal without inclusions, no cracks, transparent, unif- orm components and op- tical uniformity well. These crystals had been deal with in a high temperature annealing, single- domain polarization and after redox treatment.X-ray diffraction results show that the incorporation of Cu²⁺ alternative to 4+Nb Li, resulting in fewer defects in lithium vacancies, lattice distortions become smaller, with the increase in the number of doped copper, Cu²⁺ accounted for Li⁺ at the same time, in order to keeping the balance of charge formed the space, which increase in the number of vacancies.From Crystal UV-visible absorption spectra we can inferred: stoichiometric LiNbO₃ crystals after incorporation of copper, Cu²⁺ directly replace and occupy in the formation of Nb_Li⁴⁺. Cu⁺ replaced the normal lattice of Li⁺.From the Crystal infrared absorption spectrum, we can see that the grown single copper-doped lithium niobate crystals are near stoichiometric structure, but in the 3479cm^-1 exits lots of defects, absorption peaks relatively larger and deviation from the stoichio- metric LiNbO₃, the defect structure is Nb_Li⁴⁺- 4(V_Li)^-, OH^-absorption peak is considered that the Group of H + do the Tension vibration in the defect Nb_Li⁴⁺-OH^--3(V_Li)^-.Second-wave coupling experiment results show that a single copper-doped stoichiometric lithium niobate crystal diffraction efficiency is lower, but with the doped copper increases, the diffraction efficiency is gradually increasing, write time and erase time reduced ; through the photo-damage resistance test, we can see that with the increase in copper-doped, photo-damage resistance gradually increased, but enhanced the effect was not obvious.